This invention relates to an apparatus for blow molding hollow plastic bodies of the type comprising an openable mold, a hollow needle which can be connected to a sterile gas supply source, a sterilization chamber, and means for moving the front portion of the needle between a sterilization position within the chamber and a blow position within the mold cavity. The invention is applicable in particular to the manufacture of internally sterile receptacles, such as bottles or flasks, intended to be filled with pharmaceutical or food products.
The nature and characteristics of certain products require that they be enclosed and preserved in perfectly sterile receptacles. For these products it it therefore necessary to provide internally sterile receptacles, and to fill and close such receptacles in a sterile manner. The manufacture of such sterile receptacles in plastic is generally carried out by extruding a tubular parison or rough blank at a temperature which ensures sterilization, and then blow molding the blank with sterile air introduced through a needle traversing the wall of the blank. In order to obtain such a sterile receptacle, it is necessary that the blow needle itself be both internally and externally sterile.
In known devices of this type the sterilization chamber for the blow needle is separated from the mold and provided with an opening to allow the needle to pass therethrough. Consequently, the end of the needle may be poorly sterilized. Moreover, during transfer from the sterilization chamber to the mold and vice-versa, the needle passes through a non-sterilized area which can destroy its initial sterilization. Furthermore, the blow cycle rate is limited by problems of positioning the needle in relation to the mold.